Vacuum degassing apparatus

ABSTRACT

This disclosure relates to vacuum degassing and particularly to apparatus which uses multiple degassing vessels whereby, when one vessel is in position for degassing molten metal, the other vessel or vessels are in position for relining or preheating. The vessels are supported above ground level by a rotatable support means which carries the vessels in a circular path between the degassing zone where a vessel may be selectively lowered into and raised out of a ladle of molten metal, then to a maintenance, repair, and reheat zone where a vessel may be relined and/or preheated.

Mevissen 45] Sept.-4, 1973 VACUUM DEGASSING APPARATUS [75] Inventor: Ernst A. Mevissen, Robinson Twp.,

Allegheny, Pa.

[73] Assignee: Dravo Corporation, Pittsburgh, Pa.

[22] Filed: June 5, 1972 [2]] Appl. No.: 262,925

Primary Examiner-Gerald A. Dost Attorney-Paul Bogdon [5 7 ABSTRACT This disclosure relates to vacuum degassing and particularly to apparatus which uses multiple degassing vessels whereby, when one vessel is in position for degassing molten metal, the other vessel or vessels are in position for relining or preheating. The vessels are supported above ground level by a rotatable support means which carries the vessels in a circular path between the degassing zone where a vessel may be selectively lowered into and'raised out of a ladle of molten metal, then to a maintenance, repair, and reheat zone where a vessel may be relined and/or preheated.

13 Claims, 5 Drawing Figures PATENTEDSEP 4m: 3.756584 SHEU 2 0F 4 PATENTEUSEP 4 191a SHEEI t 0F 4 .FIG. 5.

VACUUM DEGASSING APPARATUS This invention relates to vacuum degassing apparatus and particularly to a degassing apparatus which uses multiple degassing vessels where one vessel may be positioned for degassing molten metal while the other vessel or vessels are positioned for relining and/or preheat- In the process of vacuum degassing, a ladle containing molten metal is conveyed to a degassing zone and positioned beneath a degassing chamber or vessel having depending tubular extensions or snorkels, the lower ends of which are then immersed in the molten metal. The metal is then circulated from the ladle to the degassing vessel and back to the ladle by drawing the metal up one or more of the tubes into the vessel and back to the ladle through one or more of the tubes so that undesirable gases in the metal are removed and exhausted.

The vessels used in vacuum degassing are generally lined with refractory brick and, after a period of use, the bricks must be replaced. In other words, degassing vessels are required to be relined at regular intervals. In order to maintain continuous degassing operations, metal processors have used degassing systems incorporating two degassing vessels where one vessel is used for degassing while the other is undergoing relining. A commonly used two-vessel degassing system uses track supported transfer cars for moving the vessels to and from a single degassing zone and usually two maintenance and repair areas, one each disposed on either side of the degassing zone. The transfer cars and vessels are in line with each other and move from side to side where, when one vessel is in the degassing zone, the other vessel is in one of the maintenance, repair, and preheat zones. When the relined vessel is to be used for degassing, it is moved into the degassing zone and the vessel to be relined is moved to the other maintenance, repair and preheat zone. The requirement for two maintenance, repair and preheat zones is expensive as well as requiring a considerable amount of shop space.

I overcame the dual maintenance, repair and preheat zone requirement for degassing systems by my present invention wherein my system supports multiple degassing vessels for movement along a circular path. Thus,

only one maintenance, repair and preheat zone is required. More particularly, I provide a vacuum degassing apparatus which preferably comprises: vacuum degassing means including vacuum and exhaust lines, and at least two generally vertically arranged degassing vessels provided with means for being detachably connected with the vacuum and exhaust lines; support means for supporting the vessels above ground level and in an arcuately spaced relationship with each other such that, when one vessel is in position for use in degassing molten metal, the other vessel or vessels are in an area, such as a maintenance, repair and preheat zone, away and shielded from the degassing zone; the support means being constructed and arranged for rotation about a generally vertical axis such that the vesgassing vessel support means includes platforms, each of which supports one vessel, arranged to rotate independently of each other. By such an arrangement a vessel out of operation may be moved within the maintenance, repair and preheat zone from the relining area thereof to the preheat area while the vessel in the degassing zone remains stationary. Also, in the preferred form of the invention the degassing vessels are selectively reciprocal with respect to the support means with the power means being operative with the vessel in the degassing zone to move the vessel upwardly and downwardly with respect to the ladle. There is also provided in the preferred apparatus a swinging service platform disposed in the degassing zone and arranged to swing between the top of the ladle and the degassing vessel.

' The service platform maybe used to install, change,

sels' may be transported in a generally circular path;

drive means for selectively driving the support means; ladle support means for supporting a ladle of molten metal beneath that vessel disposed in position for degassing; and power means for selectively effecting relative reciprocal movement between the vessel in the degassing zone and the ladle on the ladle support means. In the preferred form of my present invention, the deand maintain equipment in the vessel while it is in the degassing zone.

Other details and advantages of this invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings I have shown a present preferred embodiment of this invention, in which:

FIG. 1 is a somewhat diagrammatic perspective view of a vacuum degassing apparatus using a pair of degassing vessels, and embodying the present invention, with certain auxiliary equipment being eliminated for purposes of clarity of illustration;

FIG. 2 is a front elevation view of the vacuum degassing apparatus of FIG. 1 with additional details of construction being included;

FIG. 3 is a view looking along the line III-III of FIG. 2 showing more details "of construction of the vessel hoisting platform;

FIG. 4 is an enlarged elevation view, partly in section, of the right vessel carrying platform and main floor showing the details of the drive means for the platform; and

FIG. 5 is a view looking along the line V-V of FIG. 2 showing further details of construction of the parting wall between the degassing and maintenance zones and further details of construction of the service platform.

Referring now to the drawings, 10 generally refers to a vacuum degassing apparatus or system embodying the present invention. Degassing apparatus 10 includes a main support structure 12 made up of interconnected structural members arranged to support a main floor 14 disposed above ground level, a hoist floor 16, upon which hoist units are mounted, and an additive floor 18 upon which additive material storage hoppers are arranged. The main support structure 12 is constructed such that the main floor 14 is disposed in a horizontal plane located above ground level sufficiently enough to allow a ladle 20 of molten metal supported on a wheeled transfer car 22 constructed to be moved on ground-level mounted tracks 24. The ground level beneath the main floor 14 is divided'into a degassing zone 26, upon which the ladle supporting transfer car 22 is transported, and a maintainance, repair and preheat zone 28. The main floor 14 is also provided with a large circular opening 15 through which certain of the other elements of the degassing apparatus 10, may befpositionedwithin the zones 26 and 28. The zones 26 and 28 are separated by a vertical dividing wall 30'having a central section 30a extending from ground level to a point just above the upper level of the top of ladle 20. The dividing wall 30 is also provided with opposite end sections 30b which are lower than the central section 30a whereby openings are defined for permitting the vessels of the degassing apparatus to be transported between the zones 26 and 28, as will be more fully described hereinafter. The entire dividing wall 30 is formed of material which provides heat insulation between the degassing zone 26 and maintenance, repair, and preheat zone 28 so that personnel can safely and comfortably work in the maintenance zone 26 while degassing is being performed on molten metal.

The main support structure 12 also supports other auxiliary equipment such as controls arranged in control room 32 located below the main floor 14, electrical equipment room, staircases, and other miscellaneous equipment, not shown.

There is provided a pair of identical, refractory-lined degassing vessels 40 and 42 of well-known construc tion. Each of the vessels 40 and 42 includes the usual bottom section having snorkels 44 and 46 extending downwardly therefrom, one of the snorkels being an upflow tube and the other being a downflow tube. Each vessel and 42 also includes a gas exhaust or outlet housing 48 having a dust trap 50 at the lower end of the housing. The gas exhaust housing 48 is sized to telescopically receive an exhaust duct 52 connected with a vacuum creating device, such as a multistage steam injector or the like, not shown. The upper section of each vessel 40 and 42 is provided with a preheat duct 54 arranged to be mated with a vertically movable preheat unit 56, shown in FIG. 2, for providing heat to the interior of the vessels prior to degassing or preheat unit 58, shown in FIG. 1, disposed above the preheat section of the maintenance, repair and preheat zone 28 to provide heat to a vessel prior to its being transferred into the degassing zone 26. The upper section of each vessel 40 and 42 IS also provided with an additive duct sized to telescopically mate with a vertical additive chute 62 connected with additive containing bins, not shown, but normally supported on additive floor 18.

Both vessels 40 and 42 are supported for being carried in a generally circular path between the degassing zone 26 and the maintenance, repair and preheat zone 28. The vessel support includes a vertical pedestal 72 disposed in abutment with a central portion of the dividing wall 30a and on the side thereof towards the maintenance, repair and preheat zone 28. The pedestal 72 extends upwardly to a position a few feet above the top of dividing wall 30a. A vertical shaft 74 is fixed centrally of the pedestal 72 and has a stationary discshaped platform 76 fixed to the upper end thereof and extending into opening 15 of main floor 14, the top surface of the platform 76 lying in a generally horizontal plane which includes the top surface of the main floor 14. Each vessel 40 and 42 is arranged in a vessel platform 80 having a stepped shape wich an elongated fanshaped main section 81 extending radially outwardly from the platform 76. The outer radial end of each main section 81 is circular in shape and is disposed adjacent the wall of opening 15 in main floor 14 while the inner radial end of the main section is also circular in shape and is disposed adjacent the outer edge of platform 76. Each main section 81 is provided with an opening 82 sized to loosely receive a'degassing vessel 40 or 42. The vessels 40 and 42 may be freely reciprocated through the opening 82 with each vessel being provided with a flange 84 fixed to an upper section of the vessel. A plurality of downwardly extending tapered pads 86 are fixed to each flange 84, the pads having lower surfaces which extend radially beyond the opening 82 through the main section 81 of each vessel platform 80 whereby the vessel platforms will support the vessels when they are lowered so that the pads engage the vessel platforms. Each of the vessel platforms 80 includes a lower section 86 generally parallel to the main section 81 with an inclined section 88 connecting the lower and main section to each other. Each lower section 86 is arranged, one above the other, on the shaft 74 for rotation with respect thereto. Thus, each vessel platform 80 is rotatable about the vertical axis of the shaft 74.

Each of the vessel platform 80 is provided with its own drive means whereby the vessel platforms may be rotated independently of each other or synchronously as desired. The lower section 86 of the vessel platform 80, shown on the left side of FIG. 2, is provided with a downwardly extending cylindrical sleeve 90 which surrounds the shaft 74. The right lower section 86 is also provided with a downwardly extending sleeve 92 sized to surround the sleeve 90.

The outer edges of the vessel platforms 80 are arranged to be guided and supported by a circular track 94 located inwardly adjacent and below the inner edge of the opening 15 in the main floor 14. The track 94 is fixed to the upper surface of a structural member 96 supported by the main floor 14, as by a gusset plate 98 fixed between'the member 96 and the lower surface of the main floor, one of which gusset plates is shown in FIG. 4. A rotatable wheel 100 is arranged at the lower outer end surface of each vessel platform 80 and is sized and shaped to engage the track 94. Each wheel 100 is mounted on a shaft 102 of a gear reducer 103 which in turn is coupled with a reversible motor 104 connected with a source of electricity, not shown. The motor 104 and gear reducer 103 are supported to the underside of platform 80 by a support housing 105 fixed between the gear reducer and platform. Each shaft 102 is also supported by a pair of roller bearings 107 arranged in bearing housing 108 which is secured to the underside of a platform 80.

A vessel hoisting carriage 1 10 is provided for reciprocating a degassing vessel 40 and 42 when the vessel is positioned within the degassing zone 26. As shown in FIGS. 1 and 2, the vessel 40 is in position in the degassing zone 26 and is supported by the vessel hoisting carriage assembly 1 10 above the ladle 20. The vessel hoisting carriage assembly 110 has a main section 111 which, as shown in FIG. 3, is generally rectangular shaped and sized to fit above and engage the upper surface of a flange 1 12 on the upper end section of the vessels 40 and 42. Sections 113 are fixed to the back end of the main section 111 and are provided with openings whereby the tab sections are disposed to slidably surround vertical guide columns 114 supported between the main floor 14 and hoist floor 16. A pair of sheaves 116 and 118 are fixed to each end portion of the upper surface of the main section 111 with hoisting ropes 120 being reeved around the sheaves. The hoisting ropes 120 extend vertically upwardly to another pair of sheaves 122 and 124 supported on hoist floor 16 and then to motor driven hoist drum assembly 126 also supported on the hoist floor. It is noted that only one of each of the sheaves 122 and 124 is shown in FIG. 1, it being understood that there are two each of the sheaves arranged in the hoist floor 16. Three lifting pins 125 are fixed to the upper surface of the flange 112 and are arranged to be received in three openings through the main section 111 of the hoist carriage 110. Slots are provided through the upper region of the pins 125 whereby wedges 126 are inserted to lock the pins to the hoist carriage. When it is desired to raise or lower the vessel with respect to the platform 80, the hoist carriage is lowered to mate the pins with the upper section 111, and the wedges 126 are secured in place. When the vessel 40 is to be transported by the platform 80, the hoist carriage 110 is disconnected from the pins 125 and raised above the top of the vessel. Thus, the vessel hoisting carriage assembly 110 provides the means for raising and lowering the vessels 40 and 42 into and out of the ladle 20 for performing degassing operations while also permitting the vessels 40 and 42 to be transported without interference between the degassing zone 26 and the maintenance, repair and preheat zone 28.

When it is desired to shift the vessels 40 and 42 between the zones 26 and 28, the vessel 40 in the degassing zone 26 is lowered until the pads 86 engage vessel impact cushions fixed on the main section 81 of the vessel platform 80. The vessels 40 and 42 may be locked and located in place as by securing the vessel platform 80 by clamps 132, one of which is shown in FIG. 1 locking and locating the vessel 40 in place in the degassing zone 26. After any clamps being used are removed, the vessels 40 and 42 may, if desired, be locked in place on their vessel platforms 80. The vessel platforms 80 may then be driven synchronously until the vessels 40 and 42 are reversed in their positions within the respective zones 26 and 28. The vessel 40 or 42 dis- I posed within the maintenance, repair and preheat zone 28 may be moved within that zone from, for example, a bottom exchange stand shown in FIG. 2 where the bottom section of the vessel may be replaced or repaired or other work performed on the vessel. Also the vessel 40 or 42 may be relined while positioned at the bottom exchange stand 140 by removing the upper section of the vessel by lifting it with an overhead crane. After relining, the vessel 40 or 42 may be transported to align it with a preheat burner 58, shown in FIG. 1, for preheating the vessel prior to transporting it into the degassing zone 26. Transporting the vessel 40 or 42 within the maintenance, repair and preheat zone 28 may be made independently of the vessel in the degassing zone 26 which may remain fixed in position.

There is also provided a service platform 150, shown in detail in FIG. 2, arranged to swing within the degassing zone 26 for use by workers to install, repair, or change parts of the lower section of the vessels 40 or 42 while it is in the degassing zone. The service platform includes a main section 151 arranged at a level above the upper level of ladle 20 so that the ladle could be transported beneath the main section without interference. The main section 151 is fixed to a pair of arm members 153 and 154, each of which has its free end designed to surround a vertical column 156 fixed between the ground level and the underside of the control room -32. A cylindrical sleeve 158 is fixed between the free ends of the arm members 153 and 154 and also surrounds the column 156. The arm members 153 and 154 and the sleeve 158 are sized to be rotatable with respect to the stationary column 156. A ring gear 160 is fixed to an intermediate section of the sleeve 158 and meshed with a drive gear 162 fixed to the drive shaft of the motor 164 connected with a source of electricity, not shown. The motor 164 is firmly secured to another column 166 extending between the ground level and the control room 32. The main section 151 of the service platform 150 is also provided with a centrally located fixture 168 having side-by-side openings 169 and 170 sized and shaped by support snorkels 44 and 46, whereby the snorkels may be removed from the vessel 40 or 42 and carried to a position outside of the degassing zone 26 for repair or replacement. New or repaired snorkels 44 and 46 may then be conveniently transported back into position with the vessel 40 or 42 and installed in the vessel.

It should now be apparent that the degassing apparatus of my present invention as just described provides those advantages specified in the introductory portion of this specification. Other advantages will also be apparent, such as the fact that the utility and control connections may remain in place during the transportation of the vessels between the zones, and the bottom section and snorkels of a vessel may be changed without disruption of the maintenance, repair or relining operations. Also, those skilled in the art will recognize that many various modifications may be madeto theapparatus without departing from the scope of the invention. For example, the rotatable vessel support means may include a single platform with two or three vessels supported-thereby, or the ladle support may be constructed to move the ladle upwardly and downwardly within the degassing zone, rather than having the vessel reciprocate with respectto a stationary vessel.

While I have shown and described a present preferred-embodiment of thisinvention, it is to be understood that the invention is not limited thereto, but may be otherwise variously embodied within the scope of the following claims.

I claim:

1. Vacuum degassing apparatus, comprising:

vacuum degassing means including vacuum and exhaust lines, and at least two generally vertically arranged degassing vessels provided with means for being detachably connected with the vacuum and exhaust lines;

support means for supporting said vessels above ground level and in an arcuately spaced relationship with each other such that, when one vessel is in position for use in degassing molten metal, the other vessels are in an area away from the degassing zone, said supportmeans being constructed and arranged for rotation about an upright axis such that said vessel may be transported in a generally circular path; I drive means for selectively driving said support means; ladle support means for supporting a ladle of molten metal beneath one of said vessels in position for degassing suchmolten metal; and

power means for selectively effecting relative reciprocal movement between a said vessel in position for degassing and the ladle on said ladle support means.

2. The vacuum degassing apparatus as set forth in claim 1 wherein said support means includes at least two platforms, each of which supports one of said vessels, and arranged to be rotated independently of one another.

3. The vacuum degassing apparatus as set forth in claim 1 wherein said vessels are arranged for selective reciprocal movement with respect to said support means.

4. The vacuum degassing apparatus as set forth in claim 2 wherein said power means is operative with said vessels for reciprocating a said vessel in position for degassing upwardly and downwardly with respect to said ladle support means.

5. The vacuum degassing apparatus as set forth in claim 1 including a generally horizontal service platform rotatable about a generally vertical axis passing through one end thereof and arranged to move above the upper level of a ladle on said ladle support means and adjacent to the lower end of a said vessel in position for degassing.

6. In combination with a vacuum degassing apparatus including va pair of degassing vessels having means for being detachably connected with vacuum and exhaust lines, and a ladle support disposed at ground level, the invention of a vessel support apparatus comprising:

platform means for supporting the degassing vessels above ground level and in an arcuately spaced relationship with each other such that, when one vessel is in position for degassing molten metal, the other vessel will be positioned away from the degassing zone, said platform means being constructed and arranged for rotation about a generally vertical axis such that said vessels may be transported in a generally circular path; and drive means for selectively driving said platform means.

7. The vessel support apparatus as set forth in the combination of claim 6 wherein said platform means comprises a pair of separate platforms, each of which supports one of said vessels, and arranged to be rotated independently of one another.

8. The vessel support apparatus as set in the combination of claim 6 wherein said platform means supports each of said vessels such that each vessel is selectively reciprocally movable with respect to the platform means.

9. The vessel support apparatus as set forth in the combination of claim 6 including rail means arranged in a generally circular path adjacent the outer edge of said platform means, and wheel means supported by said platform means for operatively engaging said rail means.

10. Vacuum degassing apparatus, comprising:

vacuum degassing means including vacuum and exhaust lines, and a pair of generally vertically arranged degassing vessels provided with means for being detachably connected with the vacuum and exhaust lines; pair of arcuately spaced platforms arranged with their upper surfaces lying in a common generally horizontal plane, each of said platforms supporting one of said vessels above ground level, with the spacing of said platforms being such that, when one vessel is in position for use in degassing molten metal, the other vessel is in an area away from the degassing zone;

means supporting said platforms for independent rotation about a common generally vertical axis whereby said vessels will be carried by said platforms along a generally circular path; drive means for selectively driving each of said platforms;

ladle support means for supporting a ladle of molte metal in the degassing zone and beneath one of said vessels in position for degassing the molten metal; and

power means for selectively effecting relative reciprocal movement between a said vessel in position for degassing and said ladle support means.

1]. Vacuum degassing apparatus as set forth in claim 10 wherein said vessels are arranged in said platforms for selective reciprocal movement with respect to the platforms.

12. The vacuum degassing apparatus as set forth in claim 11 wherein said power means is operative with said vessels for reciprocatinga said vessel in position for degassing upwardly and downwardly with respect to said ladle support means.

13. The vacuum degassing apparatus as set forth in claim 10 including a generally horizontal service platform rotatable about a generally vertical axis passing through one end thereof and arranged to move above the upper level of a ladle on said ladle support means and adjacent to the lower end of a said vessel in position for degassing. 

1. Vacuum degassing apparatus, comprising: vacuum degassing means including vacuum and exhaust lines, and at least two generally vertically arranged degassing vessels provided with means for being detachably connected with the vacuum and exhaust lines; support means for supporting said vessels above ground level and in an arcuately spaced relationship with each other such that, when one vessel is in position for use in degassing molten metal, the other vessels are in an area away from the degassing zone, said support means being constructed and arranged for rotation about an upright axis such that said vessel may be transported in a generally circular path; drive means for selectively driving said support means; ladle support means for supporting a ladle of molten metal beneath one of said vessels in position for degassing such molten metal; and power means for selectively effecting relative reciprocal movement between a said vessel in position for degassing and the ladle on said ladle support means.
 2. The vacuum degassing apparatus as set forth in claim 1 wherein said support means includes at least two platforms, each of which supports one of said vessels, and arranged to be rotated independently of one another.
 3. The vacuum degassing apparatus as set forth in claim 1 wherein said vessels are arranged for selective reciprocal movement with respect to said support means.
 4. The vacuum degassing apparatus as set forth in claim 2 wherein said power means is operative with said vessels for reciprocating a said vessel in position for degassing upwardly and downwardly with respect to said ladle support means.
 5. The vacuum degassing apparatus as set forth in claim 1 including a generally horizontal service platform rotatable about a generally vertical axis passing through one end thereof and arranged to move above the upper level of a ladle on said ladle support means and adjacent to the lower end of a said vessel in position for degassing.
 6. In combination with a vacuum degassing apparatus including a pair of degassing vessels having means for being detachably connected with vacuum and exhaust lines, and a ladle support disposed at ground level, the invention of a vessel support apparatus comprising: platform means for supporting the degassing vessels above ground level and in an arcuately spaced relationship with each other such that, when one vessel is in position for degassing molten metal, the other vessel will be positioned away from the degassing zone, said platform means being constructed and arranged for rotation about a generally vertical axis such that said vessels may be transported in a generally circular path; and drive means for selectively driving said platform means.
 7. The vessel support apparatus as set forth in the combination of claim 6 wherein said platform means comprises a pair of separate platforms, each of which supports one of said vessels, and arranged to be rotated independently of one another.
 8. The vessel support apparatus as set in the combination of claim 6 wherein said platform means supports each of said vessels such that each vessel is selectively reciprocally movable with respect to the platform means.
 9. The vessel support apparatus as set forth in the combination of claim 6 including rail means arranged in a generally circular path adjacent the outer edge of said platform means, and wheel means supported by said platform means for operatively engaging said rail means.
 10. Vacuum dEgassing apparatus, comprising: vacuum degassing means including vacuum and exhaust lines, and a pair of generally vertically arranged degassing vessels provided with means for being detachably connected with the vacuum and exhaust lines; a pair of arcuately spaced platforms arranged with their upper surfaces lying in a common generally horizontal plane, each of said platforms supporting one of said vessels above ground level, with the spacing of said platforms being such that, when one vessel is in position for use in degassing molten metal, the other vessel is in an area away from the degassing zone; means supporting said platforms for independent rotation about a common generally vertical axis whereby said vessels will be carried by said platforms along a generally circular path; drive means for selectively driving each of said platforms; ladle support means for supporting a ladle of molten metal in the degassing zone and beneath one of said vessels in position for degassing the molten metal; and power means for selectively effecting relative reciprocal movement between a said vessel in position for degassing and said ladle support means.
 11. Vacuum degassing apparatus as set forth in claim 10 wherein said vessels are arranged in said platforms for selective reciprocal movement with respect to the platforms.
 12. The vacuum degassing apparatus as set forth in claim 11 wherein said power means is operative with said vessels for reciprocating a said vessel in position for degassing upwardly and downwardly with respect to said ladle support means.
 13. The vacuum degassing apparatus as set forth in claim 10 including a generally horizontal service platform rotatable about a generally vertical axis passing through one end thereof and arranged to move above the upper level of a ladle on said ladle support means and adjacent to the lower end of a said vessel in position for degassing. 